What to Know About Lovenox to Prevent Blood Clots During Pregnancy

pregnant woman

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While most pregnancies progress smoothly and without serious medical issues, pregnancy doesn’t come without some risk. Among the more serious risks are blood clots, or thrombosis. Pregnant people are five times as likely as non-pregnant people to experience blood clots, according to the CDC. If untreated, blood clotting during pregnancy can lead to serious conditions like pulmonary embolism (PE), which can be fatal.

Those are some scary facts, but thankfully, there are many treatment options available for blood clots during pregnancy. One of the most popular treatments is a prescription blood thinner called Lovenox, also known as enoxaparin.

If you are at high risk for blood clots in pregnancy, or if you are currently experiencing a blood clot during pregnancy, you are probably wondering if Lovenox is a good choice for you. You may be asking if Lovenox is safe for you and your growing baby, and what the side effects might be.

Here’s what we know about Lovenox, along with some helpful insight from Dr. Kim Langdon, an obstetrician-gynecologist based in Ohio.

What Is Lovenox?

The ability of our blood to clot is important and necessary (for example, after you get a cut or injury, your blood clots so that you don’t continue bleeding profusely). However, if your blood clots too much, blood clots can form in the legs and other extremities and make their way to the lungs, causing a condition called pulmonary embolism (PE), which can be life-threatening if not treated promptly.

Lovenox, or enoxaparin, is an anticoagulant (blood thinner) frequently prescribed for patients who are experiencing blood clots or are at higher risk of experiencing them in the future. One of the most common times that Lovenox is prescribed is when someone is recovering from surgery, which can increase the chances of a blood clot. It is also frequently used to treat and prevent heart attacks.

Lovenox may be given via IV when you are in the hospital, but it’s most frequently given by injection. Lovenox is injected into the fatty layer just below the skin, and is most often injected into the stomach or abdominal area. Many people learn to inject Lovenox at home, after being instructed by their healthcare provider.

The most common (but generally rare) side effects of Lovenox include:

  • Bleeding
  • Anemia
  • Thrombocytopenia (low platelet count)
  • Elevated levels of serum aminotransferase
  • Nausea and diarrhea
  • Ecchymosis (skin discoloration as a result of bleeding under the skin)
  • Edema
  • Fever
  • Shortness of breath
  • Disorientation
  • Pain at the injection site

What Are the Risks of Blood Clots in Pregnancy?

Anyone can develop a blood clot during their lifetime, but people who are pregnant have an increased risk of blood clots. In fact, their risk increases five-fold, according to the CDC. This heightened risk exists during pregnancy, delivery, and within the first three months of having a baby.

Pregnant people are more prone to blood clots during pregnancy because a pregnant person’s blood naturally clots more easily to prevent blood loss during and after giving birth. Additionally, blood may not flow as easily to the legs during pregnancy as a result of the growing fetus putting pressure on pelvic blood vessels.

The major problem with blood clots is that, if untreated, they can make their way to the lungs, causing a pulmonary embolism (PE), which can be life-threatening. The CDC explains that pulmonary embolisms top the list of pregnancy-related deaths in the U.S.

According to Dr. Langdon, some pregnant people are at higher risk of blood clots than others. Conditions that may increase your risk of blood clots during pregnancy include:

  • Family or personal history of blood clots
  • History of a blood clotting disorder
  • A C-section delivery
  • Periods of prolonged immobility, including bed rest during pregnancy or after delivery
  • Complications during pregnancy or childbirth
  • Long-term medical conditions, including heart conditions, lung conditions, or diabetes  

Lovenox During Pregnancy

If you have recently been prescribed Lovenox to manage a blood clot during pregnancy, or are at risk of experiencing a blood clot during pregnancy, you might be wondering if Lovenox is safe to take. Your concern is understandable. Anytime you take medication while pregnant, you need to make sure that it’s safe for yourself and for your growing baby.

While at this time, there isn’t much evidence about the safety of Lovenox during pregnancy, Dr. Langdon indicates that “for the most part, there are not adverse fetal or pregnancy effects.”

Dr. Langon also believes that as an anticoagulant (blood thinner), Lovenox is a better option than aspirin. She also recommends Lovenox over Herapin, another common anticoagulant sometimes given to pregnant people to prevent blood clots.

“Heparin used to be the gold standard, but more and more people are using Lovenox and the international consensus is that it should be first-line therapy due to less frequent dosing, higher bioavailability, longer half-life, more predictable response, and less laboratory testing,” she explains.

By and large, the question about whether Lovenox is right for you is something you will need to discuss directly with your healthcare provider. All pregnant people have different health histories and pregnancy risks, and your provider or midwife will be able to offer recommendations about what is best for you.

Does Lovenox Work to Prevent Blood Clots During Pregnancy?

Again, there isn’t much published evidence about Lovenox’s effectiveness in pregnancy. The most recent recommendation from the American College of Obstetricians and Gynecologists dates back to 2002. “Lovenox (enoxaparin sodium) therapy appears to be safe and efficacious for pregnant women who are candidates for either prophylactic or therapeutic heparin,” the ACOG committee opinion piece explained.

Dr. Langdon believes that Lovenox is effective at preventing clots during pregnancy, but says that the dose “may need to be adjusted upwards” for best results. Effective dosing is something to discuss with your doctor as medication dosing is often made on a case-by-case basis.

What Are the Risks of Taking Lovenox During Pregnancy?

Taking Lovenox during pregnancy has some risks. According to Dr. Langon, these risks include “excessive bleeding or bruising, vaginal bleeding, placental abruption—where the placenta pulls away from the inner wall of the uterus due to blood collection and or trauma.”

In addition, the company that manufactures Lovenox warns that pregnant people who have prosthetic heart valves should be cautious when using Lovenox, as it may result in valve thrombosis.

A Word from Verywell

Pregnancy can be a stressful time, whether or not you are dealing with a health scare. If you end up having a blood clot during pregnancy, or if you are at risk of having one, you are likely experiencing high levels of stress, discomfort, and fear. You want to know the best way to treat these blood clots and want this information as soon as possible.

As you look into treatments, including using Lovenox, your doctor or midwife will know what the best option is for you and your growing baby. Don’t hesitate to reach out to them if you need more information, or if you have additional questions.

5 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. Pregnant? Don't overlook blood clots.

  2. Centers for Disease Control and Prevention. Venous thromboembolism (blood clots) and pregnancy.

  3. Lovenox. Prophylaxis of deep vein thrombosis.

  4. Centers for Disease Control and Prevention. Pregnant? Don't overlook blood clots.

  5. American College of Obstetricians and Gynecologists. ACOG Committee Opinion: safety of Lovenox in pregnancy. Obstet Gynecol. 2002;100(4):845-846.

Additional Reading

By Wendy Wisner
Wendy Wisner is a lactation consultant and writer covering maternal/child health, parenting, general health and wellness, and mental health. She has worked with breastfeeding parents for over a decade, and is a mom to two boys.